Fresh, home-baked cookies are the standard of excellent in the cookie world. An important feature of most fresh, home-baked cookies is their texture, specifically, a crisp, friable outside surface and a ductile interior. The inside contains pockets of super-saturated sugar solution (syrup) which are ductile and are sometimes visible as strands when the warm cookie is pulled apart. Unfortunately, within a few weeks, or less, such cookies undergo a spontaneous and irreversible process of degradation, becoming hard and crumbly throughout. The following describes the physicochemical processes which occur during cookie baking and subsequent storage.
Prior to baking, a cookie dough consists of a hydrated mixture of flour, shortening (fat), sugar, and minor adjunct ingredients. During baking, sugar and water appear to be primary interactants. The flour (starch and protein) is of less importance because it holds less water, relative to the sugar, at oven temperature.
When the cookie dough enters the oven, the water in the dough is saturated with sugar and appears to be evenly distributed throughout the dough. As the water temperature increases during baking, the solubility of the sugar increases, drawing water away from the flour. At about 70.degree. C. all the water present has the capacity to dissolve all the sugar, as indicated by the fact that the X-ray diffraction pattern for crystalline sugar is lost. As the cookie temperature continues to increase (80.degree. C.), a non-saturated sugar solution is formed from which the water is free to evaporate. At this point, water is rapidly lost to the atmosphere until the solution is again saturated (0.18 gram water/gram sugar). This occurs typically after about eight minutes of baking. If baking is continued, typically to the twelve minute point, the dehydration continues and a dry (0.1 gram water/gram sugar) crunchy cookie is produced, containing amorphous sugar that cannot crystallize because its water content is too low.
When a typical cookie baked eight minutes is removed from the oven (100.degree.-105.degree. C.), most of the water is held as the hot saturated sucrose syrup. Upon cooling, this syrup becomes super-saturated, holding the water within the cookie. It is this wet syrup that gives the cookie its fresh, chewy eating quality. During the subsequent 24 hours, the sugar begins to crystallize spontaneously, and water migrates from the interior, where the water activity is relatively high, toward the moisture-depleted outer surface. During the first one to six days after baking, moisture continues to equilibrate throughout the cookie, transferring through the starch matrix. As the water activity, (A.sub.w) reaches about 0.6, the sugar is almost fully crystallized and the starch is tactilely dry. As time goes on, cross-sectional equilibrium is essentially reached. Unlike bread staling, these latter changes in a cookie cannot be reversed by heating, indicating that the starch in the cookie is not undergoing retrogradation.
It is of value, therefore, to provide cookies which, after having reached substantial textural equilibrium, still demonstrate strong texture differences between crisp regions and chewy regions. This difference should be substantial, so that it is perceivable by consumers, and storage stable, so that it is suitable for commercial production.
Currently, nearly all feasible cookie formulations which get crisp on the outside will eventually reach that same degree of crispness throughout, reverting, by water loss and sugar crystallization, to the dry, hard texture of popular ready-to-serve cookies. Most home recipe cookies will reach this totally crisp state within one or two weeks, regardless of the temperature or relative humidity at which they are stored, since the changes involved in cookie hardening are internal to the cookie and are thus independent of the cookie's external environment. Most ready-to-serve cookies are simply baked out to a crip end point immediately to facilitate subsequent handling.
Cookies can be formulated to be soft and moist by high shortening and/or high water formulas. However, such cookies have only limited microbial stability, do not stay crisp on the outside and present major problems of stickiness and crumbiness.
Another approach taken within the cookie industry has been to supply moistness impression by using coatings and/or fillings, e.g., fig bars. However, such techniques are clearly inapplicable in the case of drop-type home recipe cookies, such as chocolate chip, peanut butter, oatmeal and sugar cookies and other cookies which have a substantially homogeneous cross-section with respect to flavor and appearance.
U.S. Pat. No. 4,503,080, Brabbs and Hong, issued Mar. 5, 1985, and U.S. Pat. No. 4,455,333, Hong and Brabbs, issued June 19, 1984, describe cookies which are formed from a plurality of doughs, at least one of which contains either crystallization-resistant sugar or readily crystallizable sugar in combination with a sugar crystallization inhibitor, and at least one of which contains a conventional readily crystallizable sugar, in such a manner that the doughs remain segregated in discrete regions within the unbaked cookie. A matrix is formed which can be baked to a cookie having portions which provide a storage-stable crisp texture and portions which provide a storage-stable chewy texture.
U.S. Pat. No. 4,344,969, Youngquist et al., issued Aug. 17, 1982, describes a process for preparing cookies having storage-stable, chewy and crisp textures from a single dough wherein sugar crystallization is controlled by enzyme activity. Manipulation of water activity is one means used for activating and inactivating enzymes in selected portions of the cookie. Thus, sugars and/or starches in the areas where the enzyme is active are converted into mixtures which are non-crystallizing or crystallization-resistant, while the crystallization behavior of sucrose is preserved in those areas where the enzyme is inactive. The resulting dough and subsequent crumb areas of the baked cookie have storage-stable, chewy and crip textures, respectively.
In contrast, the present invention provides storage stable dual-textured cookies which have a sweetness profile which more closely resembles that of freshly-baked cookies.
Changing the sugar component of baked goods from the commonly used sucrose to other sugars or combinations of sugars to preserve the fresh flavor and texture of the goods is known. See, for example, "High Fructose Corn Syrup Replacement for Sucrose in Shortened Cakes", Journal of Food Science, Vol. 51, No. 2, (1986), pp. 536-37, which discloses replacement of sucrose with high fructose corn syrup to achieve moister cakes.
The use of fructose, present in invert sugars and honey, in the making of cookies is widely known among those with cooking and baking experience. In addition, fructose nominally is about 1.4 times as sweet as sucrose, and has therefore been incorporated in so-called "dietetic" baking recipes. See, for example, U.S. Pat. No. 4,137,336, S. B. Radlove, issued Jan. 30, 1979.
U.S. Pat. No. 4,233,330, Zenner, issued Nov. 11, 1980, discloses replacing 10-35% of the sugar and fat content of cake products with lactose to prolong the shelf life of the product. However, lactose is not well tolerated by many adults and is therefore not desirable in products of this type. U.S. Pat. No. 4,291,065, Zobel, issued Sept. 22, 1981, discloses a method for controlling the staling of sweet baked goods by replacing 30-100% of the sweetner composition with oligosaccharides having two or three saccharide units. This alteration may have an undesirable effect on the texture of the baked product, making it more gummy and sticky.
It has now been discovered that by making cookies from a plurality of doughs, one containing a conventional readily crystallizable sugar, and another a unique saccharide mixture which comprises monosaccharides, di- and trisaccharides, a low level of tetra- and higher saccharides, and sucrose, in such a manner that the two doughs remain segregated in discrete regions within the unbaked cookie, a matrix is formed which can be baked to a cookie having portions which provide a crisp texture and portions which provide a chewy texture.
By the practice of this invention, a texture profile is provided which is stable to aging, under normal packaging and storage conditions, and very closely approximates the organoleptic properties of a freshly baked homemade cookie. Properly executed, these cookies can be made to give the appearance of a conventional homogenous system, with little or no visual evidence of a multi-part structure.
Furthermore, by the practice of this invention, a sweetness profile is provided which very closely approximates the sweetness properties of a freshly baked home-made cookie.
It is therefore an object of this invention to provide a crumb-continuous dual-textured cookie having an improved sweetness profile, mouthmelt and dissipation, and extended shelf stability.